exo·​sphere | \ ˈek-sō-ˌsfir How to pronounce exosphere (audio) \

Definition of exosphere

: the outer fringe region of the atmosphere of the earth or a celestial body (such as a planet)

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Other Words from exosphere

exospheric \ ˌek-​sō-​ˈsfir-​ik How to pronounce exospheric (audio) , -​ˈsfer-​ How to pronounce exospheric (audio) \ adjective

Examples of exosphere in a Sentence

Recent Examples on the Web

The problem is that if there really are 1,000 ions per cubic centimeter, the ionization of gas in the lunar exosphere can’t account for such a high concentration—there just isn’t enough gas. Daniel Oberhaus, WIRED, "Lunar Mysteries That Science Still Needs to Solve," 16 July 2019 In the 1970s two Soviet lunar orbiters discovered that ions also existed in the moon’s ultra-thin exosphere, and scientists have been trying to explain this observation ever since. Daniel Oberhaus, WIRED, "Lunar Mysteries That Science Still Needs to Solve," 16 July 2019 Instead scientists refer to its extremely thin covering of oxygen, hydrogen, sodium, helium, and potassium as an exosphere. National Geographic, "The solar system, explained," 27 Mar. 2019 Because nitrogen is a volatile chemical, some of it sublimates and gives Pluto a tenuous atmosphere still thick enough to be more than an exosphere. John Wenz, Popular Mechanics, "Here's What We Know About Pluto So Far," 17 July 2015 The spacecraft has two spectrometers that will be analyzing the exosphere. Joe Pappalardo, Popular Mechanics, "4 More Hurdles the LADEE Moon Mission Must Clear," 9 Sep. 2013 Team Unsullied seemed poised for a predictable victory, when suddenly — his square jawline visible from the exosphere — along came dependable ol’ Jaime Lannister, sacking Highgarden and laying waste to Dany’s plans at the last minute. Anna Silman, The Cut, "I’m Rooting for the Lannisters," 4 Aug. 2017 Giant Steps set a new benchmark for virtuosity and harmonic complexity, a manned probe into jazz’s exosphere. Julian Sancton, Billboard, "Remembering Jazz's Greatest Year With the Living Legends of 1959," 5 May 2017 And charged particles in the exosphere can be carried around and away from the planet by the magnetic field. Lisa Grossman, WIRED, "Mercury Flyby Maps New Territory," 15 July 2010

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'exosphere.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of exosphere

1949, in the meaning defined above

History and Etymology for exosphere

exo- + -sphere

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Statistics for exosphere

Last Updated

13 Aug 2019

Look-up Popularity

Time Traveler for exosphere

The first known use of exosphere was in 1949

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More Definitions for exosphere


exo·​sphere | \ ˈek-sō-ˌsfir How to pronounce exosphere (audio) \

Kids Definition of exosphere

: the outermost region of the atmosphere

More from Merriam-Webster on exosphere

Rhyming Dictionary: Words that rhyme with exosphere

Britannica.com: Encyclopedia article about exosphere

Comments on exosphere

What made you want to look up exosphere? Please tell us where you read or heard it (including the quote, if possible).


a usually brief trip or an expedition

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